Rotary kiln and furnace



Oct. 30, 1928.

J. H. BENTLEY v ROTARY KILN AND FURNACE 2 Sheets-Sheet Filed- Sept. 9,1926 J. H. BENTLEY ROTARY KILN AND FURNACE Oct. 30, 1928.

Filed Sept. .9, 1926 ZSheetS-Sheet' 6 R. O w w m Patented Oct. 30, 1928.

UNITED STATES JOHN HENRY BENTLEY, 0F MISTERTON, ENGLAND.

ROTARY KILIN' AND Application filed September 9, 1926, Serial No'.

This invention relates to rotary kilns and furnaces of the type in whichthe heat extracted in cooling the material is used to preheat the airand fuel supplied to the combustion zone of the kiln or furnace, theobject of the invention being to provide improved means for obtainingthis recuperatorefi'ect and to increase the output and reduce the fuelconsumption.

In kilns used for burning cement materials there is usually a drying orpreheating zone at the feed end followed by a calcining zone and asintering zone where combustion of the fuel takes place adjacent to thedischarge end. It is known to provide a preliminary cooling chamber ofgreater diameter than the sintering zone between that zone and a centraldischarge orifice and according to the present invention lifting ductsare fitted at the end of such a cooling chamber and formed withscoop-like openings. at its circumference. A delivery cone, provided bya conical or inclined guide closes the inner ends ofrthe lifting ductsto the interior of the kiln and opens them to the exterior, and arecuperator chamber is furnished below the discharge orifice connectedthereto by a pipe or cowl having a packed joint around the orifice.Cascaders may be provided in the cooling chamber.

The recuperator chamber preferably contains an inner cellsurmounted by aconical spreader (which may be fitted with spikes) and the chamber isformed with a hopper-like base. Cooling air is supplied to the cell andissues therefrom through ports into an annular passage between cell andchamber, and if desired an encased. conveyor may be provided below thebase of the recuperator chamber, cooling air being supplied to thechamber also through the conveyor casing.

Fuel is preferably blown into the kiln by a fan or blower deriving itsair from the recuperator chamber and connected to a pipe extendingco-axially through the delivery cone and through the preliminary coolingchamber. Secondary combustion air passes into the kiln from therecuperator chamber through the lifting ducts which may be provided withapertures through their inner walls to deliver this air nearer to thecentre of the preliminary cooling chamber. A renewable sleeve isconveniently fitted on the fuel pipe adjacent to the delivery cone toprotect it from damage by the falling clinker.

In the accompanying drawing I other by radial fins 11 of the being acontinuation of one or 134,545, and in Great Britain J'anuai'y 8, 1926.

Figure 1 is a longitudinal section elevation of the delivery end of arotary kiln or furnace. according to the present invention.

Flgure 2 is a half end view and transverse section of Figure 1.

Like reference numerals indicate like parts throughout the drawing.

The drying or preheating and calcining zones of the kiln are notillustrated, Figure 1 showing the end of the sintering zone 3. Beyondthis zone the kiln is continued with a somewhat greater diameter toprovide a prehminary cooling chamber-4 which is closed at the end by asuitable cover 5 having a central discharge orifice as shown in Figure 1and being fitted with a circular track 6 supported on rollers 7.

Gascaders 8 are shown inside the preliminary cooling chamber 4 arrangedto lift the material therein as they revolve with the kiln, preferablyonly to such a height that the view of the operator is notobscuredthrough the upper portion. The cascaders 8 do not extend to the extremeend of the preliminary cooling chamber 4, and in this cylindrical endportion thereof is arranged a series of hollow lifting ducts 9 rotatingwith the chamber. The lifting ducts 9 are formed with scoop-likeopenings at the circumference of the chamber 4 and extend therefrom to adelivery cone 10 at the central discharge orifice, the delivery cone 10comprising conical or inclined guides closing the inner ends of thelifting ducts 9 to the interior of the kiln and opening them to theexterior.

The hollow lifting ducts 9 may be radial to the cooling chamber 4 asshown in the sectional half of Figure 2 or they may be curved at theirouter ends as shown in dotted lines in the left-hand half of Figure 2.They may either be radial or tangential or otherwise disposed inrelation to the delivery cone 10. The openings of the lifting ducts 9 tothe delivery cone 10 are separated from one ane, these fins 1 both ofthe side walls of the lifting ducts or separate therefrom as may bedesired.

A stationary recuperator chamber 12 is disposed at a lower level thanthe preliminary 106 cooling chamber 4, below its central dischargeorifice, and is connected to the latter by a suitable -ipe or cowl 13having a packed joint as in icated at 14 around the delivery orifice,the packing being such as to allow for the 1 expansion and contractionof the kiln as well as for its rotation.

The recuperator chamber 12 contains an inner cell 15 carried by girders16 and surmounted by a conical spreader 17 which may be fitted withpointed spikes 18, the spreader being disposed in the path of materialfalling from the delivery cone 10 through the connecting pipe 13. Belowthe cell 15 the recuperator chamber is formed with a hopperlike base 19by means of which the material is delivered through a suitable valve ordamper 20 to a conveyor 21 or to an elevator, wagons or other suitablemeans of transport.

Cold air is supplied to the inner cell 15 by means of a blower or fan 22through a pipe 23 and passes through ports or holes 24 in the lowerportion of the cell into anannular space 25 between the cell 15 andwalls of the recuperator chamber 12 which is preferably covered with asuitable heat insulating material (not illustrated). If desired a branch26 from the fan pipe 23 may be connected to a casing 27 enclosing theconveyor 21 transporting the material from the base of the recu ratorchamber 12, such air passing into the chamber through the valve 20.

The coal dust or other fuel is supplied through a pipe 28 and is blowninto the kiln by a fan or blower 29 deriving its air supply from therecuperator chamber 12 and connected to a pipe 30 which extends acrossthe connecting pipe 13, through the delivery cone 10 with which it isco-axial and through the centre of the preliminary cooling chamber 4 sothat the fuel is burnt in the sintering zone 3. A renewable sleeve 31 isreferably fitted on the pipe 30 adjacent to t e delivery cone 10 toprotect it from damage due tothe material falling thereon.

In operation the material may be treated in the rotary kiln as usual,but preferably its passage therethrough is retarded by conical portionsas described in my specification No. 591 of 1926. On leaving thesintering zone 3 the material is cascaded in the preliminary coolingchamber 4 and gives up a portion of its heat to the air passingtherethrough. On arrivin at the extreme end it is lifted by the hol owducts 9 and delivered on to the discharge cone 10 whence it passes intothe recuperator chamber 12 falling through the annular passage 25provided by the inner cell 15 and being broken by the spikes 18 and thespreader 17. During this fall it is meeting the upward stream of airfrom the interior of the cell 15 and from the base 19, and this air isthus heated and delivered into the preliminary cooling chamber 4 throughthe hollow lifting ducts 9 whence it passes into the kiln to 'providethe secondary air for the combustion of the fuel, primary combustionair, of course, being derived also from the coolin chamber 12 and theamounts being contro ed by dampers or throttle valves 32.

If desired the hollow lifting ducts 9 may be formed with apertures 33for delivering the air nearer to the centre of the preliminary coolingchamber 4;.

WVhat I claim is 1. In a rotary kiln or furnace having a preliminarycooling chamber between the sintering zone and a central dischargeorifice the combination with lifting duct-s at the end of the coolingchamber having scoop-like openings at its circumference, of a deliverycone provided by a conical or inclined guide closing their inner ends tothe interior of the kiln and opening them to the exterior, substantiallyas specified.

2. In a rotary kiln or furnace having a preliminary cooling chamberbetween the sintering zone and a central discharge orifice thecombination with cascaders in the cooling chamber, of lifting ducts atthe end of the cooling chamber having scoop-like openings at itscircumference, and a delivery cone provided by a conical or inclinedguide closing their inner ends to the interior of the kiln and openingthem to the exterior, substantially as specified.

3. In a rotary kiln or furnace having a preliminary cooling chamberbetween the sintering zone and a central discharge orifice thecombination with lifting ducts at the end of the cooling chamber havingscoop-lilac openings at its circumference, of a delivery cone providedby a conical or inclined guide closing their inner ends to the interiorof the kiln and opening them to the exterior and a recuperator chamberbelow the discharge orifice connected thereto by a pipe or cowl having apacked joint around the discharge orifice, substantially as specified.

4. The combination with a rotary kiln or furnace having a centraldischarge orifice of a recuperator chamber below such orifice connectedthereto by a substantially gas tight passage and containing an innerhollow cell surmounted by a conical spreader with an annular passagebetween cell and chamber extending to a hopper-like base of the chamber,means for supplying cooling air to the cell and ports putting theinterior of the cell into communication with such annular passage,substantially as specified.

5. The combination with a rotary kiln or furnace having a centraldischarge orifice of a recuperator chamber below such orifice connectedthereto by a substantially gas tight passage and containing an innerhollow cell surmounted by a conical spreader with an annular passagebetween cell and chamber extending to a hopper-like base of the chamber,means for supplying cooling air to the cell, ports putting the interiorof the cell into communication with such annular passage, an encasedconveyor below the base of the chamber, a valve providing communicationbetween the said base and the conveyor an means for supplying coolingair to the chamber through the conveyor casing, substantially asspecified.

6. In a rotary kiln oriurnace having a preliminary cooling chamberbetween the sinterin zone and a central discharge orifice, the coinination with cascaders in the cooling chamber, lifting ducts at the endof the cooling chamber having scoop-like openings at its circumference,a delivery cone provided by a conical or inclined guide closing theirinner ends to the interior of the kiln and opening them to the exterior,a r'ecuperator chamber below the discharge orifice connected thereto bya pipe or cowl having a acked joint around the dischar e orifice, aollow cell surmounted by a conical spreader inside the chamber with anannular passage between cell and chamber extendingtoahopperlike base ofthe chamber, means for suppl ing coolin air to the cell, ports putting te interior 0 the cell into communication with such annular p e, anencased conveyor below the base of the chamber, a valve providincommunication between the said base and e conveyor, means for supplyingcooling air to the chamber through the conveyor casin a fan deriving airfrom the recuperator c amber, a pipe connected to the fan and extendinco-axially through the delivery cone an through the preliminary coolingchamber and a renewable sleeve on such pipe adjacent to the deliverycone, substantially as specified.

In testimony whereof I hereunto afiix my signature.

JOHN HENRY BENTLY.

